No motor carrier of passengers subject to 49 U.S.C. subtitle IV, part B shall in the operation of vehicles in interstate or foreign commerce utilize any terminal facility in which there is not conspicuously displayed and maintained so as to be readily visible to the public a plainly legible sign or placard containing the full text of these regulations. Such sign or placard shall be captioned: “Public Notice: Regulations Applicable to Vehicles and Terminal Facilities of Interstate Motor Carriers of Passengers, by order of the Secretary, U.S. Department of Transportation.”